Unable to create site with custom URL

Hi 

I am learning sharepoint as part of exercise, I am trying to create a basic site that has a custom URL. My machine name is adityabmachine and if I try to create a website with this as a base url, everything works smooth. But I am trying to create an intranet site with a custom URL as below:

http://msforum:1010/

 that will have subsites like:
http://msforum:1010/sites/microsoft

I was able to create site collection as above. But the URL doesn't open.

Please help!

Thanks

Aditya

http://easytipsandtricks.com

aditya